His death was announced on air by his BBC Radio 2 friend and colleague Bob Harris, who took over presenting his Sounds of the 70s show in November.
Walker had previously worked for Swinging Radio England, Radio Caroline and BBC Radio 1 and spent time living and broadcasting in San Francisco.
The DJ retired in October due to ill health having been previously diagnosed with idiopathic pulmonary fibrosis (IPF), a condition affecting the lungs.
Walker had been working with the Stars Appeal – the charity for Salisbury District Hospital – since its launch in February 2007.
Johnnie Walker (left) with Nick Carty, the surgeon who saved his lifeWalker underwent emergency surgery at the hospital in 2003 after he collapsed at his Dorset home with a malignant bowel growth.
At the charity’s launch, he said: “The doctors and nurses at Salisbury District Hospital literally saved my life.
“It’s a fantastic place and the lovely people who work there have got huge pride in the hospital and in the work they do.”
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On New Year’s Day, Dave Cates of the Stars Appeal posted: “We are greatly saddened by the news that our long-time patron and great friend and supporter Johnnie Walker MBE has passed away.
“Johnnie became a patron of the Stars Appeal upon our launch in 2007, having been cared for at the hospital during his cancer treatment some years earlier.
“Johnnie’s attendance at many of our fundraising events and celebrations of completed projects over nearly 20 years supporting the charity, always accompanied by his wife Tiggy, helped make these occasions extra special and his work for us played a key role in raising our profile both locally and nationally.
“In 2009, he gave a special performance of his touring show at Salisbury Arts Centre to raise funds for the new Children’s Unit, which to this day continues to help thousands of local children and families.
“We will miss Johnnie greatly and we send our deepest sympathies and love to Tiggy and all their family and friends.”
Johnnie Walker with Dave Cates of the Stars Appeal at An Evening With Johnnie Walker at Salisbury Arts Centre in 2009 (Image: Salisbury Newspapers) Walker’s wife Tiggy said: “I couldn’t be more proud of Johnnie – how he kept broadcasting almost to the end and with what dignity and grace he coped with his debilitating lung disease.
“He remained his charming, humorous self to the end. What a strong, amazing man. It has been a rollercoaster ride from start to finish.
“God bless that extraordinary husband of mine, who is now in a place of peace.”